Castor recon in mMR Biograph

General Discussions
1

Hi, I have defined three types of phantom in Gate ( simple sphere , Microhollow4sphere and microPET NEMA phantom) , all filled with the same activity as the real experiments , except for simple sphere which I want to use it for sanity checks and that is also filled with 10 Mbq activity.

however when I get my image files ( interfile images as an output of Castor) and I analyse them with Amide , the activity concentration doesnt match with what I have defined in Gate(basicially around 10^8 times smaller).

I know I have to apply some sort of Calibration factor or normalisation but I dont know how>?and where? can you please help me with this if you have any idea

thank you
Elnaz

2

Hi,

You have to do as in the real life.

Simulate an acquisition of a cylindrical phantom with a known activity concentration. Acquire enough data. Reconstruct without quantification factor. Measure. Compare. And deduce a quantification factor that you then input into the header of castor datafiles.

Best
Simon

| Elnaz
November 14 |

  • | - |

Hi, I have defined three types of phantom in Gate ( simple sphere , Microhollow4sphere and microPET NEMA phantom) , all filled with the same activity as the real experiments , except for simple sphere which I want to use it for sanity checks and that is also filled with 10 Mbq activity.

however when I get my image files ( interfile images as an output of Castor) and I analyse them with Amide , the activity concentration doesnt match with what I have defined in Gate(basicially around 10^8 times smaller).

I know I have to apply some sort of Calibration factor or normalisation but I dont know how>?and where? can you please help me with this if you have any idea

thank you
Elnaz